1. Field of the Invention
This invention relates to a pressure-sensitive adhesive structure (or structural body) having a superior weathering resistance.
2. Description of the Prior Art
Pressure-sensitive adhesive structures comprising a polyvinyl chloride film coated with a pressure-sensitive adhesive or comprising a polyethylene film coated with a pressure-sensitive adhesive, have been hitherto used as pressure-sensitive adhesive structures such as pressure-sensitive adhesive films and pressure-sensitive adhesive sheets.
The above conventional pressure-sensitive adhesive structures, however, have a poor weathering resistance, and hence may seriously undergo a lowering of properties, as exemplified by a color change, a decrease in surface gloss, a decrease in bending strength, a lowering of elongation, or a decrease or loss of adhesive force, when they are used outdoors. They also tend to cause peeling, contamination, and so forth. For example, pressure-sensitive adhesives mainly composed of natural rubbers or synthetic rubbers, used in conventional pressure-sensitive adhesive tapes, have a poor weathering resistance and thus may seriously undergo color changes and deterioration of properties.
Even with use of an acrylic pressure-sensitive adhesive, having a relatively high weathering resistance, no sufficient weathering resistance can be still obtained. Moreover, this acrylic pressure-sensitive adhesive has the disadvantages that it can adhere to non-polar surfaces with difficulty and has a small adhesive force at a low temperature.